Eyeball gloss not visible behind another glass object
Ok I tested your setup and found your mistake. The outer ball material is more or less correct (You can omit the reflection ray handling). The problem is the inner reflection material of the eye. Just remove everything you have done with Light Paths in that material and it should work perfectly fine.

EDIT:
Also you should change out the Glass BSDF for a Glossy BSDF in the eye reflection. At least I found it to work better.